Offset



March 31, 1964 R. R. BROWN 3,127,044

OFFSET LOWER ANVIL FOR AN AUTOMATIC RIVETTING MACHINE Filed NOV. 20, 1962 2 Sheets-Sheet 1 F ig.l

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INVENTOR. RICHARD R. BROWN mad w March 31, 1964 R. R. BROWN 3,127,044

OFFSET LOWER ANVIL FOR AN AUTOMATIC RIVETTING MACHINE a Filed Nov. 20, 1962 2 Sheets-Sheet 2 llll fie I 8 I Mr "51:5 I! f 49"- 9 ZZ/IUI Fig.6 g -s Fig.7

INVENTOR. RICHARD R. BROWN BY I 141;, & 141m United States Patent ,0 "ce 3,127,044 OFFSET LOWER ANVIL FOR AN AUTOMATIC RIVETTING MACHINE Richard R. Brown, San Diego, Calif., assignor to Brown Tool Engineering Company, El Cajon, Calif. Filed Nov. 20, 1962, Ser. No. 238,956 3 Claims. (Cl. 218-1) The present invention relates generally to machine tools and more particularly to an olfset lower anvil for an automatic rivetting machine.

The primary object of this invention is to provide a lower anvil for a rivetting machine incorporating a material clamping yoke which operates smoothly and without binding, yet retains accurate alignment during prolonged use.

Another object of this invention is to provide an anvil wherein the movable clamping yoke is constructed so that the dimensional tolerances involved are not unduly critical and the parts can be made fully interchangeable.

Another object of this invention is to provide a lower anvil which is adaptable to many existing rivetting machines without requiring modifications to the machines.

Finally, it is an object to provide a rivetting machine anvil of the aforementioned character which is simple and convenient to construct and install and which will give generally efiicient and durable service.

With these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully described in the specification, particularly pointed out in the claims, and illustrated in the drawings which form a material part of this disclosure, and in which:

FIGURE 1 is a side elevation view of the basic structure of a1 typical rivetting machine incorporating the lower anv1 FIGURE 2 is an enlarged side elevation view of the anvil;

FIGURE 3 is a front elevation view thereof;

FIGURE 4 is a top plan view of the anvil;

FIGURE 5 is an enlarged sectional view taken on line 55 of FIGURE 2;

FIGURE 6 is a sectional view taken on line 66 of FIGURE 3; and

FIGURE 7 is an enlarged sectional view taken on line 7-7 of FIGURE 6.

Similar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawing.

Basic Machine Structure The anvil, generally indicated at 10, is fixed to the lower jaw 12 of a rivetting machine 14, which has a generally V-shaped frame 16 defining a deep throat and having an upper arm 18, as in FIGURE 1. On the end of upper arm 18 is a rivetting head 20 which is lowered to form a rivet against the lower anvil. The specific structure of the rivetting machine and its operating mechanism may vary considerably, the basic principles being well known and the present lower anvil being adaptable to various machines.

Conventionally, the rivetting machine has a lower anvil with a fixed portion carrying a button to hold the rivet being formed, the button being shaped to hold the preformed head of the rivet and the other end of the rivet being upset or formed by the descending element of the rivetting head. In order to hold the parts being rivetted tightly together while the rivet is being upset, the lower anvil has clamping elements which are biased against the parts and retract under the pressure of the rivetting head.

3,127,044 Patented Mar. 31, 1964 It is these clamping elements which are problematic, since the movement must be smooth with clamping action maintained and the limits of travel must be closely held to ensure proper clamping throughout a rivetting cycle. The dimensional tolerances which must be met in conventional structures are restrictive and interchangeability of parts is usually impractical.

Lower Anvil Structure The lower anvil 10 comprises a generally rectangular back plate 22 at the upper end of which is a forwardly protruding anvil tongue 24 having a socket 26 to hold a conventional rivet head button, not shown. The anvil is thus offset. forwardly from the frame 16, which facilitates the use of various attachments. The tongue 24 is supported by downwardly extending reinforcing webs 28 at the sides thereof, with an open channel 38 therebetween extending to the bottom of back plate 22. For strength and practical purposes, the tongue 24 has a solid body portion 32 integral with back plate 22, the tip portion of said tongue containing socket 26 being of reduced width to minimize obstruction in the area of rivetting.

Mounted on the anvil is a clampnig yoke 34 comprising a pair of plates 36 on opposite sides of body portion 32 and having clamping jaws 38 projecting upwardly at the sides of tongue 24. The plates conform to the shape of body portion 32 and tongue 24, with the clamping jaws 38 closely spaced on either side of socket 26. In the body portion 32 is a vertical bore 40 opening into channel 30 and in which is a slidable piston 42.

Through the piston is a connecting pin 44 fixed to the plates 36, the connecting pin 44 extending through vertically elongated slots 46 in the sides of the body portion and coextensive with bore 40, so that the entire clamping yoke 34 is vertically slidable. The ends of pin 44 have shoulders 43 against which the plates 36 are held by screws 45 through end caps 47 on the outside of said plates, the length of said pin between the shoulders spacing plates 36 for a close sliding fit over the body portion 28. On the inner faces of plates 36 are full depth vertical guide ribs 48 which ride in grooves 49 cut in hardened inserts 50, which are recessed in body portion 32 and held by screws 51, as in FIGURE 5. The ribs 48 and grooves 49 maintain the alignment of the clamping yoke 34 and a close sliding fit is necessary. However, due to the substantial length of ribs 48 the tolerances are not unduly high and interchangeability is practical.

The length of slots 46 limits the travel of the clamping yoke 34, but the width of the slots is not critical since the connecting pin 44 does not guide the yoke.

Operation On the rivetting machine 14 a cushion unit 52 is mounted below anvil 10 with a push rod 54 engaging the lower end of piston 42. The cushion unit 52 may be spring biased, pneumatic, or hydraulic depending on the type of machine and is used to bias the clamping yoke 34 upwardly.

The parts 56 and 58 to be rivetted together are placed in position over anvil 10, as in FIGURE 1, resting on top of clamping jaws 38 with the unformed end of a rivet 60 projecting upwardly. The rivetting head 20 is then actuated to press the parts downwardly, the pressure retracing the clamping yoke 34, as indicated in broken line in FIGURES 2 and 3, until the upper ends of jaws 38 are flush with the upper face of tongue 24. The downward travel of yoke 34 is limited by the connecting pin 44 reaching the bottom of slots 46, pressure still being maintained to clamp the parts together. The rivet 60 is then upset by continued action of the rivetting head 20. Some machines may have slightly different sequential actions and utilize special holding mandrels and rivet setting devices, but the general procedure is substantially as described. The clamping yoke 34 is accurately guided by ribs 48 in grooves 49 and maintains an even pressure of the jaws 38 against the work parts.

The plates 36 can be replaced by others with different jaw shapes or lengths for clamping particular parts, or performing specialized rivetting operations. The reasonable tolerances required ensure that various clamping yokes will operate smoothly on a common anvil. The hardened inserts 50 are esaily replaceable when worn and make frequent replacement of the lower anvil itself unnecessary.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawings are to be considered as merely illustrative rather than limiting.

I claim:

1. An olfset lower anvil for use on a rivetting machine, comprising:

a back plate for attachment to the machine;

a forwardly extending anvil tongue on said back plate,

said tongue having a socket in the upper face thereof to receive a rivet holding button;

a clamping yoke mounted on said anvil tongue, said clamping yoke having plates on opposite sides of said tongue with clamping jaws extending upwardly therefrom;

a vertical bore through said tongue;

elongated slots on both sides of said tongue coextensive with said bore;

a piston slidable in said bore;

a pin through said piston and said slots and interconnecting said plates;

said tongue having grooves parallel to the axis of said piston;

and said plates having ribs smoothly slidable in said grooves to guide and align said yoke.

2. A lower anvil according to claim 1, wherein said pin has shoulders at opposite ends against which said plates are secured and are spaced by said pin to fit closely over said anvil.

3. An offset lower anvil for use on a rivetting machine, comprising:

a back plate for attachment to the machine;

a forwardly extending anvil tongue on said back plate, said tongue having a socket in the upper face thereof to receive a rivet holding button;

a clamping yoke straddling said tongue and having upwardly projecting clamping jaws on either side of the tongue;

said tongue having replaceable hardened inserts with grooves therein perpendicular to the upper face thereof;

and said clamping yoke having ribs smoothly slidable in said grooves to guide and align the yoke.

References Cited in the file of this patent UNITED STATES PATENTS 195,603 Heyl Sept. 25, 1877 2,394,346 Wiedman Feb. 5, 1946 2,408,330 Miller Sept. 24, 1946 

1. AN OFFSET LOWER ANVIL FOR USE ON A RIVETTING MACHINE, COMPRISING: A BACK PLATE FOR ATTACHMENT TO THE MACHINE; A FORWARDLY EXTENDING ANVIL TONGUE ON SAID BACK PLATE, SAID TONGUE HAVING A SOCKET IN THE UPPER FACE THEREOF TO RECEIVE A RIVET HOLDING BUTTON; A CLAMPING YOKE MOUNTED ON SAID ANVIL TONGUE, SAID CLAMPING YOKE HAVING PLATES ON OPPOSITE SIDES OF SAID TONGUE WITH CLAMPING JAWS EXTENDING UPWARDLY THEREFROM; A VERTICAL BORE THROUGH SAID TONGUE; ELONGATED SLOTS ON BOTH SIDES OF SAID TONGUE COEXTENSIVE WITH SAID BORE; A PISTON SLIDABLE IN SAID BORE; A PIN THROUGH SAID PISTON AND SAID SLOTS AND INTERCONNECTING SAID PLATES; SAID TONGUE HAVING GROOVES PARALLEL TO THE AXIS OF SAID PISTON, AND SAID PLATES HAVING RIBS SMOOTHLY SLIDABLE IN SAID GROOVES TO GUIDE AND ALIGN SAID YOKE. 